Plant protein hydrolysates are commonly used as food flavoring agents. Thus, WO 94/25580 and K. Pommer, Cereal Foods World, 745 (1995) describe the hydrolysis of plant protein with a fungal protease preparation containing five or more proteolytic enzyme components, to produce a flavoring agent with a high degree of hydrolysis.
The prior art has suggested various ways of modifying or improving the flavor of plant protein hydrolysates. Thus, U.S. Pat. No. 3,689,277 (to Bio-Technical Resources) and JP-A 52-41274 (Kikkoman) describe processes for modifying the flavor of a protein hydrolyzate by adding a sugar (mono- or disaccharide) and heating. The prior art has also suggested the use of carbon treatment or flash treatment to improve the flavor of protein hydrolysates (MacLeod, G., Critical reviews in Food Science and Nutrition, 27, 4, 219-400).
U.S. Pat. No. 5,130,149 discloses the manufacture of coffee flavoring substances by a process comprising enzymatic hydrolysis of soya meal with a protease, followed by heating to 140-200.degree. C. for 0.5-5 hours.
U.S. Pat. No. 5,141,757 discloses the production of a flavoring agent by a process comprising treating a protein material with a protease, heating to 90-140.degree. C. for 10 seconds -30 minutes (the shortest time corresponding to the highest temperature and vice versa), cooling and treating with enzymes from koji.
The prior art also describes the treatment of plant material with proteases for various other purposes not related to food flavoring agents, such as proteinaceous products for use as functional protein or nutritional products where a low degree of hydrolysis (DH) is desired, e.g. U.S. Pat. No. 5,100,679.
It is the object of this invention to provide an improved method of modifying the flavor of a food flavoring agent made by the hydrolysis of plant protein material with proteases without the need for adding sugar and without the need for using excessive temperatures.